The invention relates to a basket filter made of perforated metal foil which is developable in one plane, with a form which merges from a round opening into a straight-line bottom edge, particularly for coffee-makers.
Conical basket filters are already known, in which the filter surface consists of a circular bottom part and a shell region in the form of a sector of a circular ring. Filters of this type have the disadvantage that a relatively large amount of waste occurs in the manufacturing of the individual metal foil parts. This is especially unfavourable in the galvanoplastic manufacture of the metal film parts and in gold-plating of these (German Offenlegungsschrift No. 2,217,341).
It is also known to manufacture basket filters of the type mentioned in the introduction from a onepiece metal foil part which has a butterfly-shaped outline. Even this design fails to ensure good utilisation of a metal foil.